Lipoxygenase and Allene Oxide Cyclase from Leymus: Cloning and Expression Analysis in Wheat-Leymus Chromosome Addition Lines

The American dune grass Leymus mollis (Triticeae; Poaceae) is a wild relative of wheat (Triticum aestivum L.) that is highly tolerant to biotic and abiotic stresses. L. mollis is useful as genetic resource for wheat breeding via wide hybridization that allows integration of its useful traits. To clarify the genetic mechanisms controlling its physiological tolerance, we used suppression subtractive hybridization and differentially screened L. mollis subtracted cDNA libraries generated from plants subjected to drought or salt stress. We identified allene oxide cyclase (AOC) and lipoxygenase (LOX) genes which are involved in the biosynthesis of jasmonic acid (JA), an important signaling compound that mediates wide range of adaptive responses. In addition to drought and salt stresses, the expression patterns of both LmAOC and LmLOX were upregulated under jasmonic acid and abscisic acid treatments. Moreover, LmAOC was rapidly induced under heat, cold and wounding stresses. Further characterization showed that LmAOC is a multiple-copy gene in the genome of L. mollis, and that some copies were conserved and efficiently expressed in wheat-Leymus chromosome addition lines in response to different abiotic stresses. Our results suggest that expression of these genes may play a crucial role in L. mollis tolerance to abiotic stresses, and they could be useful for wheat improvement.